The present invention relates to a power generation apparatus and its control method, and more particularly, to a power generation apparatus, having a solar cell and a power transducer such as an inverter, to supply alternating power to a commercial power system and a load, and a control method for the apparatus.
As the variety of power supply forms increases, a private power generation apparatuses such as a solar cell, a wind power generator, a fuel buttery and an engine power generator attract public attention. Especially, the low-pollution solar cell is popular as a convenient power generation apparatus.
In recent years, a system interconnection type solar photovoltaic system which converts power generated by the solar cell to alternating power by an inverter and supplies the power to a commercial power system (hereinbelow, referred to as a xe2x80x9csystemxe2x80x9d) and an independent type solar photovoltaic system which supplies alternating power to a load are widely used. Especially, a solar cell module with inverter (hereinbelow referred to as an xe2x80x9cAC modulexe2x80x9d) disclosed in Japanese Published Unexamined Patent Application No. Hei 10-14111 receives attention as a middle and small size solar photovoltaic apparatus or an emergency power source. The AC module is a solar cell module where a small inverter called a Module Integrated Converter (MIC) is attached to a rear surface or the like of solar cell module, and is capable of outputting alternating power by single module.
The AC module as described above is connected to a distribution panelboard by a crimp contact or the like at the end of its lead. If a fault occurs in the AC module, or if an abnormal condition occurs in the system, an interconnection relay in the AC module is opened, thereby the AC module is disconnected from the system.
Further, as shown in FIG. 1, a construction to supply power generated by a solar cell via an outlet to a load or the like has been proposed. In use of an AC module 105 as shown in FIG. 1, a user merely inserts a plug 106 provided at the end of lead of the AC module 105 into an outlet 107, to supply power to a load 109 or the like.
In the solar photovoltaic system in FIG. 1, an inverter 101 of the AC module 105 has an interconnection relay 102. If an abnormal condition occurs in a solar cell 103, the inverter 101 or a system 104, the interconnection relay 102 is opened, thereby the system 104 (and the load 109) is disconnected from the AC module 105.
However, the solar photovoltaic system as shown in FIG. 1 has the following problems.
(1) The interconnection relay 102 in the inverter of the AC module 105 increases the size of the inverter.
(2) As the disconnection between the AC module and the system 104 upon occurrence of abnormal condition is made in the AC module 105, the user cannot easily check the disconnection status.
(3) It is preferable that the user who checked a fault in the AC module 105 operates a branch switch 111 or the like in the distribution panelboard 108 to disconnect the system 104 from the AC module 105, however, this is very troublesome work.
(4) It is preferable that upon occurrence of abnormal condition or fault, the user pulls the plug 106 of the AC module 105 out of the outlet 107, however, the plug 106 might remain plugged.
The present invention has an object to solve the above-described problems individually or at once, and to attain downsizing of the inverter in the AC module.
Further, another object of the present invention is to facilitate checking of disconnection between the AC module and the system upon occurrence of abnormal condition.
Further, another object of the present invention is to disconnect the system from the AC module upon occurrence of a fault in the AC module.
Further, another object of the present invention is to pull the plug of the AC module from an outlet upon occurrence of abnormal condition or fault.
To attain the above objects, the present invention provides a power generator comprising: a power converter which converts direct current power into alternating current power; a connector which connects an output of said power converter to a commercial power system or a load; and a signal outputting section which supplies a signal to release connection to said connector.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same name or similar parts throughout the figures thereof.